Apparatus and a method for controlling a head-up display of a vehicle

ABSTRACT

An apparatus (101), a method (1000), a system (120), a vehicle (103), a computer program (904) and a non-transitory computer readable medium (906) for controlling ahead-up display (102) of a vehicle (103) are disclosed. The apparatus (101) comprises control means (104) configured to obtain positional data representative of a position of an eye (105) of a user (106) of the vehicle (103), obtain environment data representative of the environment (107) external to the vehicle (103); and obtain status data representative of a current position (803) of the vehicle (103). The control means is also configured to determine a proposed position (804) and proposed orientation in dependence on the environment data and the status data, and in dependence on the proposed position (804), the proposed orientation and the positional data, generate image data for the head-up display (102) for causing the head-up display (102) to display a virtual object (108) so as to appear at the proposed position (804) and with the proposed orientation with respect to the environment (107).

TECHNICAL FIELD

The present disclosure relates to an apparatus and a method forcontrolling a head-up display of a vehicle. In particular, but notexclusively it relates to an apparatus and a method for controlling ahead-up display of a road vehicle such as a car.

Aspects of the invention relate to an apparatus, a method, a system, avehicle, a computer program and a non-transitory computer readablemedium.

BACKGROUND

Head-up displays in vehicles are known which display, to a user of thevehicle, navigational guidance, driver assist systems, driving relatedvehicle information (e.g. speedometer, cruise control), and non-drivingrelated information from the infotainment system (e.g. media, phone andsettings content). A problem with some existing systems is that thedisplayed information may be difficult for some users to interpret. Ithas been proposed to display an image of a car or an alternativeobject/graphic in a head-up display, which the user is then able tofollow along a route. However, a potential problem with such displays isthat the displayed image does not appear to be correctly positioned inthe exterior environment or is not animated correctly within theexterior environment. Furthermore, a potential problem is that thedisplayed car may appear to move out of a correct position when the usermoves their head. Such characteristics may become distracting and becomea source of irritation to the driver of the car.

It is an aim of the present invention to address one or moredisadvantages of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide an apparatus, a method,a system, a vehicle, a computer program and a non-transitory computerreadable medium as claimed in the appended claims.

According to an aspect of the invention there is provided an apparatusfor controlling a head-up display of a vehicle, the apparatus comprisingcontrol means configured to: obtain positional data representative of aposition of an eye of a user of the vehicle; obtain environment datarepresentative of the environment external to the vehicle; obtain statusdata representative of a current position of the vehicle; determine aproposed position and proposed orientation in dependence on theenvironment data and the status data; and in dependence on the proposedposition, the proposed orientation and the positional data, generateimage data for the head-up display for causing the head-up display todisplay a virtual object so as to appear at the proposed position andwith the proposed orientation with respect to the environment.

This provides the advantage that the virtual object appears to becorrectly positioned and oriented within the environment external to thevehicle even when the user moves his or her head. Also the virtualobject may be animated in a way that is naturalistic and thereforeconveys information to the user without causing a distraction.

In some embodiments, the status data is representative of a currentorientation of the vehicle and the control means is configured togenerate image data in dependence on the current orientation of thevehicle.

In some embodiments the image data generated for the head-up display isfor causing the head-up display to display the virtual object so as toappear at the proposed position and with the proposed orientation withrespect to the environment from the position of the an eye of a user ofthe vehicle.

According to another aspect of the invention there is provided anapparatus for controlling a head-up display of a vehicle, the apparatuscomprising control means configured to: obtain positional datarepresentative of a position of an eye of a user of the vehicle; obtainenvironment data representative of the environment external to thevehicle; obtain status data representative of a current position andcurrent orientation of the vehicle; determine a proposed position for anobject in dependence on the environment data and the status data; and independence on the proposed position, the positional data and currentorientation of the vehicle, generate image data for the head-up displayfor causing the head-up display to display a virtual object so as toappear at the proposed position with respect to the environment.

This provides the advantage that the virtual object appears to becorrectly positioned within the environment external to the vehicle evenwhen the user moves his or her head.

In accordance with a further aspect of the present invention there isprovided an apparatus for controlling a head-up display of a vehicle,the apparatus comprising an electronic processor, and an electronicmemory device electrically coupled to the electronic processor andhaving instructions stored therein, wherein the processor is configuredto access the memory device and execute the instructions stored thereinsuch that it becomes configured to: obtain positional datarepresentative of a position of an eye of a user of the vehicle; obtainenvironment data representative of the environment external to thevehicle; obtain status data representative of a current position andcurrent orientation of the vehicle; determine a proposed position andproposed orientation for an object in dependence on the environment dataand the status data; and in dependence on the proposed position, theproposed orientation, the positional data and current orientation of thevehicle, generate image data for the head-up display for causing thehead-up display to display a virtual object so as to appear at theproposed position and with the proposed orientation with respect to theenvironment.

According to a still further aspect of the invention there is providedan apparatus for controlling a head-up display of a vehicle, theapparatus comprising control means configured to: obtain environmentdata representative of the environment external to the vehicle; obtainstatus data representative of a current position and current orientationof the vehicle; determine a proposed position and proposed orientationfor an object within the environment in dependence on the environmentdata and the current position of the vehicle; and in dependence on theproposed position, the proposed orientation and current orientation ofthe vehicle, generate image data for the head-up display for causing thehead-up display to display a virtual object so as to appear at theproposed position and with the proposed orientation with respect to theenvironment.

This provides the advantage that the virtual object may be animated in away that is naturalistic and therefore conveys information to the userwithout causing a distraction.

In some embodiments the environment data comprises route datarepresentative of a route for the vehicle, the proposed position is onthe route and the proposed orientation is indicative of a directionalong the route.

This provides the advantage that the virtual object is able to guide auser along a route in a manner that is easily understood to all users.

In some embodiments the control means is configured to obtain speed datarepresentative of a current speed of the vehicle; and determine theproposed position and proposed orientation in dependence on theenvironment data, the current position of the vehicle and the currentspeed of the vehicle.

This provides the advantage that the virtual object may be made toappear to travel in front of the vehicle at a speed that depends on thespeed of the vehicle.

In some embodiments the control means is configured to adjust theapparent distance between the vehicle and the virtual object.

This provides the advantage that head-up display is able to convey anindication of required changes in speed in a naturalistic manner.

The term “apparent distance” is the distance to an object perceived by auser in view of any of the size, perspective, lateral or verticalposition, of an image of the object as provided by a head-up display.

In some embodiments the control means is configured to: determine fromthe environment data a proposed speed for the vehicle at the proposedposition; and to decrease the apparent distance between the vehicle andthe virtual object in dependence on the current vehicle speed beinggreater than the proposed speed.

This provides the advantage that head-up display is able to convey anindication of required reduction in speed in a naturalistic manner.

In some embodiments the control means is configured to decrease theapparent distance between the vehicle and the virtual object independence on the environment data being indicative of the vehicleapproaching a section of the road/route having at least one of: a legalspeed limit which is less than the current speed of the vehicle; a bend;a road junction; and traffic moving slower than the vehicle.

In some embodiments the control means is configured to: determine fromthe environment data a proposed speed for the vehicle at the proposedposition; and to increase the apparent distance between the vehicle andthe virtual object in dependence on the current speed of the vehiclebeing less than the proposed speed.

This provides the advantage that head-up display is able to convey anindication that speed of the vehicle may be increased in a naturalisticmanner.

In some embodiments the control means is configured to increase theapparent distance between the vehicle and the virtual object up to apredefined maximum value.

In some embodiments the control means is configured to increase theapparent distance between the vehicle and the virtual object independence on the environment data being indicative of the vehicleentering a section of the road/route having a legal speed limit which isgreater than the current speed of the vehicle and/or in dependence onthe environment data being indicative of the vehicle leaving a sectionof the road/route having at least one of: a bend; a road junction; andtraffic moving slower than the vehicle.

In some embodiments the control means is configured to: adjust or reducea brightness of the virtual object in dependence on a determination thatan obstruction is at the proposed position or between the vehicle andthe proposed position.

This provides the advantage that confusion between the real world andthe virtual object is avoided.

In some embodiments the control means is configured to: prevent thedisplay of the virtual object in dependence on a determination that anobstruction is at the proposed position or between the vehicle and theproposed position.

This provides the advantage that the user is not presented with a viewof the virtual object being superimposed over another real-world objectand therefore the user has a clearer view of the obstruction. Forexample, where the obstruction is a vehicle and the virtual objectprovides a view of a vehicle, the user is not presented with a confusingview of a simulated vehicle being superimposed over a real vehicle.

In some embodiments the control means is configured to display analternative graphical element to the virtual object in dependence on adetermination that an obstruction is at the proposed position or betweenthe vehicle and the proposed position.

This provides the advantage that the user may still be provided withinformation, such as navigational information, even when the usualvirtual object is not displayed.

In some embodiments the alternative graphical element comprises anindication of a direction of the route for the vehicle.

In some embodiments the control means is configured to determine theproposed position and the proposed orientation for a 3-dimensionalobject and to generate the image data for displaying the virtual objectfrom a 3-dimensional model of the 3-dimensional object in dependence onat least one of: the positional data; the current orientation of thevehicle; and the proposed orientation.

In some embodiments the control means is configured to determine aproposed position and proposed orientation for the 3-dimensional objectand to generate the image data for displaying the virtual object from a3-dimensional model of the 3-dimensional object in dependence on thepositional data, the current orientation of the vehicle and the proposedorientation.

This provides the advantage that the user may be presented with views ofthe 3-dimensional object which are like those expected of a real3-dimensional object present in the exterior environment.

In some embodiments the virtual object comprises a 2-dimensional virtualobject.

In some embodiments the control means is configured to display analternative graphical element in dependence on the proposed positionbeing outside of a limit of the head-up display in which the virtualobject is not present in a field of view of the head-up display.

This provides the advantage that when the head-up display has a limitedfield of view, so that it cannot display the virtual object in allrequired positions, it is still able to provide information to the userby displaying the alternative graphical element.

In some embodiments the alternative graphical element provides anindication of the direction of a route for the vehicle.

This provides the advantage that the user may still be provided withessential navigational information, even when the head-up display cannotdisplay the usual virtual object due to its limited field of view.

In some embodiments the control means is configured to: determine, fromthe environment data, positions along a route where it is necessary tochange direction or to turn onto a different road or to change of laneon a road while the vehicle is driven; and generate image data to causean indication on the head-up display to provide a warning that a changein direction or a turn onto a different road or a change of lane isabout to be required.

In some embodiments the virtual object is a representation of a vehicle,and the indication on the head-up display comprises flashing directionindicators (or turn signals).

In some embodiments the control means is configured to receiveenvironment data from at least one of: a satellite navigation modulecomprising a digitally stored map; one or more distance sensors; a radarsystem, a lidar system, and a camera. In some embodiments the one ormore distance sensors are ultrasonic sensors. In some embodiments theultrasonic sensors are configured to function as parking sensors and/orAutonomous Emergency Braking (AEB) sensors. In some embodiments thecamera comprises a stereo camera. In some embodiments the cameracomprises a mono camera.

In some embodiments the control means is configured to determine thecurrent position and/or the current orientation of the vehicle from dataobtained from a satellite navigation device.

In some embodiments the control means is configured to determine thecurrent position and/or the current orientation from data obtained fromone or more of: an inertial measurement unit (IMU), an accelerometer; agyroscope and an odometer.

In some embodiments the control means comprises an electronic processorand a electronic memory device coupled to the electronic processor andhaving instructions stored therein.

According to another aspect of the invention there is provided a systemcomprising a head-up display and the apparatus of any one the previousparagraphs, wherein the apparatus is configured to provide an outputsignal to the head-up display to cause the head-up display to displaythe virtual object.

In some embodiments the system comprises an imaging means configured tocapture an image containing a representation of an eye of a user of thevehicle, and processing means configured to generate the positional datain dependence on the captured image.

According to further aspect of the invention there is provided a vehiclecomprising the system of any one of the previous paragraphs or theapparatus of any one of the previous paragraphs.

According to yet another aspect of the invention there is provided amethod of controlling a head-up display of a vehicle, the methodcomprising: obtaining positional data representative of a position of aneye of a user of the vehicle; obtaining environment data representativeof the environment external to the vehicle; obtaining status datarepresentative of a current position of the vehicle; determining aproposed position and proposed orientation in dependence on theenvironment data and the status data; and in dependence on the proposedposition, the proposed orientation and the positional data, generatingimage data for the head-up display for causing the head-up display todisplay a virtual object so as to appear at the proposed position andwith the proposed orientation with respect to the environment.

This provides the advantage that the virtual object appears to becorrectly positioned and oriented within the environment external to thevehicle even when the user moves his or her head. Also the virtualobject may be animated in a way that is naturalistic and thereforeconveys information to the user without causing a distraction.

In some embodiments, the status data is representative of a currentorientation of the vehicle and the method comprises generating the imagedata in dependence on the current orientation of the vehicle.

In some embodiments the environment data comprises route datarepresentative of a route for the vehicle, the proposed position is onthe route and the proposed orientation is indicative of a directionalong the route.

In some embodiments the method comprises: obtaining speed datarepresentative of a current speed of the vehicle; and determining theproposed position and proposed orientation in dependence on theenvironment data, the current position of the vehicle and the currentspeed of the vehicle.

In some embodiments the method comprises adjusting the apparent distancebetween the vehicle and the virtual object.

In some embodiments the method comprises: determining from theenvironment data a proposed speed for the vehicle at the proposedposition; and decreasing the apparent distance between the vehicle andthe virtual object in dependence on the current vehicle speed beinggreater than the proposed speed.

In some embodiments the method comprises decreasing the apparentdistance between the vehicle and the virtual object in dependence on theenvironment data being indicative of the vehicle approaching a sectionof the road/route having at least one of: a legal speed limit which isless than the current speed of the vehicle; a bend; a road junction; andtraffic moving slower than the vehicle.

In some embodiments the method comprises: determining from theenvironment data a proposed speed for the vehicle at the proposedposition; and increasing the apparent distance between the vehicle andthe virtual object in dependence on the current speed of the vehiclebeing less than the proposed speed.

In some embodiments the method comprises: adjusting or reducing abrightness of the virtual object in dependence on a determination thatan obstruction is at the proposed position.

In some embodiments the method comprises: preventing the display of thevirtual object in dependence on a determination that an obstruction isat the proposed position or between the vehicle and the proposedposition.

In some embodiments the method comprises displaying an alternativegraphical element to the virtual object in dependence on a determinationthat an obstruction is at the proposed position or between the vehicleand the proposed position.

In some embodiments the alternative graphical element comprises anindication of a direction of the route for the vehicle.

In some embodiments the method comprises determining a proposed positionand a proposed orientation for a 3-dimensional object and generating theimage data for displaying the virtual object from a 3-dimensional modelof the 3-dimensional object in dependence on the positional data, thecurrent orientation of the vehicle and the proposed orientation.

In some embodiments the virtual object comprises a 2-dimensional virtualobject.

In some embodiments the method comprises displaying an alternativegraphical element in dependence on the proposed position being outsideof a limit of the head-up display in which the virtual object is notpresent in a field of view of the head-up display.

In some embodiments the alternative graphical element provides anindication of the direction of a route for the vehicle.

In some embodiments the method comprises: determining, from theenvironment data, positions along a route where it is necessary to turnonto a different road or to change of lane on a road; and generatingimage data to cause an indication on the head-up display to provide awarning that a turn onto a different road or a change of lane are aboutto be required.

In some embodiments the method comprises receiving environment data fromat least one of: a satellite navigation module comprising a digitallystored map; one or more distance sensors; a radar system, a lidarsystem, and a camera.

In some embodiments the method comprises determining the currentposition and/or the current orientation of the vehicle from dataobtained from a satellite navigation device.

In some embodiments the method comprises determining the currentposition and/or the current orientation from data obtained from one ormore of: an inertial measurement unit (IMU), an accelerometer; agyroscope and an odometer.

In some embodiments the method comprises providing an output signal tothe head-up display to cause the head-up display to display the virtualobject.

In some embodiments the method comprises capturing an image containing arepresentation of an eye of a user of the vehicle, and generating thepositional data in dependence on the captured image.

The virtual object may be a representation of a vehicle, and the vehiclebrake lights in the representation may be selectively illuminated toprovide an indication to a user that a reduction in speed is required.The vehicle direction indicators (or turn signals) in the representationof the vehicle, may be selectively illuminated to provide a warning thata change in direction or a turn onto a different road or a change oflane is about to be required.

Within the scope of this application it is expressly intended that thevarious aspects, embodiments, examples and alternatives set out in thepreceding paragraphs, in the claims and/or in the following descriptionand drawings, and in particular the individual features thereof, may betaken independently or in any combination. That is, all embodimentsand/or features of any embodiment can be combined in any way and/orcombination, unless such features are incompatible. The applicantreserves the right to change any originally filed claim or file any newclaim accordingly, including the right to amend any originally filedclaim to depend from and/or incorporate any feature of any other claimalthough not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by wayof example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a vehicle comprising an embodiment of an apparatus inaccordance with the invention;

FIG. 2 is a first perspective view from a seat of the vehicle shown inFIG. 1 illustrating an operational use of the apparatus;

FIG. 3 is a second perspective view from a seat of the vehicle shown inFIG. 1 illustrating an operational use of the apparatus;

FIG. 4 is a third perspective view from a seat of the vehicle shown inFIG. 1 illustrating an operational use of the apparatus;

FIG. 5 is a fourth perspective view from a seat of the vehicle shown inFIG. 1 illustrating an operational use of the apparatus;

FIG. 6 is a fifth perspective view from a seat of the vehicle shown inFIG. 1 illustrating an operational use of the apparatus;

FIG. 7 is a block diagram illustrating an embodiment of a head updisplay system in accordance with the invention;

FIG. 8 is a plan view of the vehicle shown in FIG. 1;

FIG. 9 is a schematic diagram of the apparatus shown in FIG. 1;

FIG. 10 is a flowchart illustrating an embodiment of a method inaccordance with the invention;

FIG. 11 is a flowchart illustrating additional processes included withinthe method of FIG. 10 in an embodiment of the invention;

FIG. 12 is a flowchart illustrating additional processes included withinthe method of FIG. 10 in an embodiment of the invention;

FIG. 13 is a flowchart illustrating additional processes included withinthe method of FIG. 10 in an embodiment of the invention;

FIG. 14 is a flowchart illustrating an additional process includedwithin the method of FIG. 10 in an embodiment of the invention;

FIG. 15 illustrates a user's view of a virtual object, which isdisplayed on a tilted plane, in accordance with an embodiment of theinvention; and

FIG. 16 illustrates a different view of the virtual object displayed onthe tilted plane shown in FIG. 15.

DETAILED DESCRIPTION

The Figures illustrate an apparatus 101 for controlling a head-updisplay 102 of a vehicle 103, the apparatus 101 comprising control means104 configured to: obtain positional data representative of a positionof at least one eye 105 of a user 106 of the vehicle; obtain environmentdata representative of the environment 107 external to the vehicle 103;obtain status data representative of a current position of the vehicle103; determine a proposed position and proposed orientation for anobject in dependence on the environment data and the current position ofthe vehicle 103; and in dependence on the proposed position, theproposed orientation and the positional data, generate image data forthe head-up display 102 for causing the head-up display 102 to display avirtual object 108 so as to appear at the proposed position and with theproposed orientation with respect to the environment.

In the illustrated embodiments, the status data is also representativeof a current orientation of the vehicle and the control means isconfigured to generate image data in dependence on the currentorientation of the vehicle.

FIG. 1 illustrates the vehicle 103 comprising a head-up display system120 and the apparatus 101. The head-up display system 120 comprises thehead-up display 102. The apparatus 101 comprises a control means 104 forcausing the head up display to display the virtual object 108. Thehead-up display 102 comprises an image display device 109 and an opticalsystem 110 configured to project light from the image display deviceonto a windshield 111 of the vehicle 103, where it is reflected towardsthe eyes 105 of a user 106 of the vehicle 103. Thus, in the illustratedembodiment, the windshield 111 is configured to provide the function ofa combiner of the head-up display 102.

In the illustrated embodiment, the head-up display 102 is arranged toproject light towards the eyes of a user 106 seated in a driver's seat112 of the vehicle 103. However, it is envisaged that the head-updisplay 102 may be arranged to project light towards the eyes of a userseated in any seat of the vehicle 103, such as a front or rear passengerseat, for example.

The optical system 110 is configured to produce the virtual object 108which appears to the user 106 as a virtual object 108 positioned infront of the vehicle 103 and within the exterior environment 107 aheadof the vehicle 103. The image displayed by the head up display 102 iscontrolled by the control means 104 in dependence of data it obtainsfrom environment sensing means 113 located within the vehicle 103 andpositional data it obtains from images captured by imaging means 114,also located within the vehicle 103.

The environment sensing means 113 comprises means for determining theposition and orientation of the vehicle 103 within the environment 107to provide status data representative of the current position andcurrent orientation of the vehicle 103 to the control means 104. Theenvironment sensing means 113 also comprises means for determiningfeatures of the environment 107 external to the vehicle 103 as isdescribed below with reference to FIG. 7.

The imaging means 114 comprises one or more cameras configured tocapture images of the user's head 115 which include a representation ofone or more eyes 105 of the user 106. The captured images are analysedto determine where in the image at least one of the eyes 105 arepositioned. This process may be performed by a processor within the oneor more cameras forming the imaging means 114 or may be performed byanother processor of the apparatus 101. After determining the positionof the representation of the user's eyes 105 within an image thisinformation is processed to determine positional data representative ofa position within the vehicle 103 of at least one eye 105 of the user106.

A view from a seat 112 through the windshield 111 of the vehicle 103 isshown in FIG. 2. The head-up display 102 (shown in FIG. 1) presentsimages to a user within a field of view 201 (represented by arectangular dotted outline). In the illustrated embodiment, the head-updisplay 102 presents a virtual object 108 which illustrates a view of a3-dimensional object 202 to the user 106 (shown in FIG. 1), so that theobject 202 appears to be within the exterior environment 107 on a routebeing taken by the vehicle 103. In the illustrated embodiment, theobject 202 has the appearance of a vehicle in the form of a car 202.

The vehicle 103 comprises a navigation device 203 with a user interface204 to enable a user of the vehicle 103 to enter details of a route or adestination for the vehicle 103. The navigation device 203 may comprisea satellite navigation device comprising a receiver for receivingsignals in a global navigation satellite system (GNSS) such as a GlobalPositioning System (GPS). The navigation device 203 may also comprisedata storage means, such as a flash memory device, storing one or moremaps in a digital form, and a route planner configured to determine aroute in dependence of the current position of the vehicle 103 and auser selected destination.

Under the control of the control means 104 (shown in FIG. 1) the head-updisplay 102 is arranged to display the car 202 such that it appears to auser of the vehicle 103 as if it were a real car driving along the routedetermined by the navigation device 203 of the vehicle 103. As shown inFIG. 2, the head-up display 102 is arranged to display the car 202 suchthat it has an apparent position which is ahead of the vehicle 103.Consequently, the user 106 (shown in FIG. 1) of the vehicle 103 is ableto follow the displayed car 202 as if it were a real car driving on theuser's intended route.

To ensure that the displayed car 202 appears to the user 106 to becorrectly positioned and oriented with respect to the exteriorenvironment 107, the head-up display system 120 (shown in FIG. 1)includes the imaging means 114 and references the positional dataobtained from the imaging means 114 to enable positioning dataindicative of the position of the user's eyes 105 to be determined.Thus, when the user 106 moves their eye position, the displayed car 202does not appear to move from its correct position and orientation in theenvironment 107. For example, in FIG. 2, the displayed car 202 appearsto the user 106 as being on a road surface 205 and pointing in adirection in which it appears to be travelling.

In the example of FIG. 2, the vehicle 103 is travelling at a speedtypical of highway driving and the displayed car 202 has the appearanceof a car 202 that is about 8 metres ahead of the vehicle 103. Otherdistances between the vehicle 103 and the apparent position of the car202 are envisaged.

The head-up display system 120 (shown FIG. 1) is configured to providewarnings to the user 106 of changes in speed and direction that will ormay be required for the vehicle 103 to travel on a determined route. Forexample, when the environment sensing means 113 provides data indicativeof a feature or features of the environment ahead that require areduction in speed when compared to the current speed of the vehicle103, the control means 104 is arranged to cause the head-up display 102to provide an indication of the required reduction in speed. The controlmeans 104 may do this by providing an immediate visual indication, suchas causing brake lights on the displayed car 202 to be illuminated. Inaddition, the control means 104 causes the dimensions of the displayedcar 202 to increase so that it appears to the user 106 that thedisplayed car 202 is getting closer to the vehicle 103 due to braking.

Similarly, when the environment sensing means 113 provides dataindicative of a feature or features of the environment ahead that allowan increase in speed when compared to the current speed of the vehicle103, the control means 104 is arranged to cause the head-up display 102to provide an indication of the increase in speed. The control means 104may do this by providing causing the dimensions of the displayed car 202to decrease so that it appears to the user 106 that the displayed car202 is getting further from the vehicle 103 due to acceleration.

In the illustrated embodiment, the head-up display 102 is configured toenable the presentation of the virtual object 108 at apparently varyingdistances in front of the vehicle 103. The varied distances to thevirtual object 108 may be achieved by moving the virtual image generatedby the head-up display 102 in a road perspective-oriented plane of thehead-up display 102. For example, in an embodiment the head-up display102 is a “tilted-plane” head-up display, in which the virtual objectappears to the user to be located on a plane that is tilted to thevertical.

An example of a virtual object 108, in the form of the car 202,displayed so that it appears on a tilted plane 1501 is shown in a firstview from a position of a user in FIG. 15. FIG. 16 illustrates theorientation of the tilted plane 1501 relative to a direction, which isrepresented by an arrow 1502 and which is substantially perpendicular toa road surface on which the vehicle (103 in FIG. 1) is located. In theembodiment illustrated in FIGS. 15 and 16, additional graphical elementsrelating to the speed of the vehicle (103 shown in FIG. 1) are displayedon a second plane 1505 which is substantially parallel to the arrow1502.

The tilted plane 1501 is positioned so that a first edge 1503, which isnearest to the user (106 shown in FIG. 1), is at a first height and theheight of the tilted plane 1501 increases as the distance from the firstedge 1503 increases, up to a second edge 1504, which is furthest fromthe user. Thus, the virtual object 108 can be moved away from the firstedge 1503 towards the second edge 1504, resulting in the virtual objectappearing to move away from the user 106, or the virtual object 108 canbe moved towards the first edge 1503 away the second edge 1504,resulting in the virtual object appearing to move towards the user 106.While the virtual object 108 is moved in this way, it is scaled in acorresponding manner i.e., the dimensions of the virtual object 108 arereduced as it is moved away from the first edge 1503 and increased as itis moved towards the first edge 1503. By varying the apparent distanceof the virtual object 108 and altering its size in a correspondingmanner, a depth to the display is conveyed to the user 106.

Therefore, to enhance the appearance of the displayed car 202 gettingcloser due to braking, the head-up display 102 is also caused to reducethe apparent distance to the virtual object 108. Similarly to enhancethe appearance of the displayed car 202 getting further away due toaccelerating, the head-up display 102 is caused to increase the apparentdistance to the virtual object 108. In an embodiment, the head-updisplay is configured to enable the presentation of the virtual object108 at an apparent distance ranging from about 2 metres to about 8metres. However, other embodiments are envisaged in which the apparentdistance is varied between limits other than 2 metres and 8 metres.Adjusting these limits may be appropriate in dependence on the vehicleand the height of the user's eyes above the ground, for example,increasing the limits for a tall statured vehicle with a correspondinglyhigh driving position and decreasing them for a vehicle with a very lowseating position.

A second example of a view through the windshield 111 of the vehicle 103is shown in FIG. 3. Specifically, FIG. 3 shows a view at a time when theenvironment sensing means 113 has detected that a feature or features ofthe environment ahead require a reduction in speed of the vehicle 103.Consequently, the head-up display 102 displays the car 202 withilluminated brake lights 301, and the car appears to be larger andcloser, due to it braking. By illuminating the brake lights 301 andproviding the appearance of the displayed car 202 starting to slow down,the head-up display system 120 warns the user 106 that, at the apparentposition of the displayed car 202, he or she will also have to brake.

In the example shown in FIG. 3, the need for braking has arisen due toan upcoming turn from the current road 302 onto a side road 303.Consequently, under the control of the control means 104, the head-updisplay 102 has also been caused to start displaying a flashingindicator light (or turn signal) 304 on the displayed car 202 when thedisplayed car 202 appears to be within a suitable distance of the turn.Therefore, the user 106 of the vehicle 103 is warned of the need to turnonto the side road 303 and also prompted to indicate their intention toturn, to other road users, at the position where the displayed car 202started indicating.

A third example of a view through the windshield 111 of the vehicle 103is shown in FIG. 4. Specifically, FIG. 4 shows a view at a time when thevehicle 106 is approaching a junction where the side road 303 meets themain road 302. In this instance, the car 202 is displayed, at a positionand orientation, as if it is travelling around a bend 401 from the mainroad 302 onto the side road 303, in the manner of a real car.

To achieve this, the control means 104 (shown in FIG. 1) is configuredto determine a proposed position and proposed orientation for thedisplayed car 202 in dependence on environment data obtained from theenvironment sensing means 113. The environment data includes datadefining: the location and configuration of the junction; the route,which in this case extends from the main road 302 onto the side road303; and the current position of the vehicle 103. The proposed positionof the displayed car 202 is shown in FIG. 4. However, the proposedposition of the front of the car 202 is outside of the field of view 201and consequently only a rear portion of the car 202 is displayed on thehead-up display 102.

In the present embodiment, to simulate the movements of a real car bythe displayed car 202, the control means 104 is configured to determinea proposed position and proposed orientation for a 3-dimensional modelof the car 202 and to generate the image data for the virtual object 108from the 3-dimensional model. In the present embodiment, the head-updisplay 102 is configured to present a 2-dimensional virtual object 108to the user 106, but the image data is determined from the 3-dimensionalmodel of the car 202, and therefore the user 106 is presented with viewsof the displayed car 202 as if it were a 3-dimensional object locatedwithin the environment external to the vehicle 103.

A fourth example of a view through the windshield 111 of the vehicle 103is shown in FIG. 5. Specifically, FIG. 5 shows a view at a time when thevehicle 103 has almost reached the junction where the side road 303meets the main road 302. In this instance, the proposed position of thecar 202 is such that the region in which the car 202 should be displayedis completely outside of a limit of the head-up display 102 (shown inFIG. 1), i.e. the proposed position of the car 202 is no longer withinthe field of view 201 of the head-up display. However, to ensure thatthe user 106 is kept informed of the correct route, in dependence on thecar 202 not being displayed, the control means 104 (shown in FIG. 1) isconfigured to cause the head-up display 102 to display an alternativegraphical element in the form of an arrow 501 to indicate that the usershould turn at the junction.

A fifth example of a view through the windshield 111 of the vehicle 103is shown in FIG. 6. Specifically, FIG. 6. shows a view at a moment whenan obstruction, in the form of another vehicle 601, is at a proposedposition for the car 202 or is between the position of the vehicle 103and the proposed position for the car 202. The control means 104 may beconfigured to change the appearance of the virtual object 108 independence on a determination that an obstruction 601 is at the proposedposition, or between the vehicle 103 and the proposed position. Forexample, the brightness of the virtual object 108 may be adjusted, forexample reduced, in such circumstances. Additionally, or alternatively,the colour of the virtual object may be altered and/or the virtualobject may be changed to an alternative graphic. In the presentembodiment, the brightness of the virtual object 108 is arranged to bereduced to zero, to prevent the display of the virtual object.

This typically may happen when the vehicle 103 slows down or stops whenapproaching a junction. However, in the present embodiment the controlmeans 104 is configured to cause the display of an alternative graphicalelement 602 instead of the vehicle 202 as the virtual object independence on a determination that an obstruction is at the proposedposition, or between the vehicle 103 and the proposed position. Thus,for example, the control means 104 may be configured to cause an arrow602 to be displayed, to indicate the proposed route to the user 106, inthe absence of the car 202 being displayed. In the example shown in FIG.6, an upward pointing arrow 602 is being displayed to indicate to theuser 106 that the proposed route is straight on.

In the examples shown in FIGS. 2 to 6, the virtual object 108 is arepresentation of a car 202, but it will e appreciated that the virtualobject 108 could take the appearance of a different type of vehicle inalternative embodiments. Alternatively, the virtual object 108 couldhave the appearance of an object other than a vehicle.

A block diagram illustrating functional components of an embodiment ofthe head up display system 120 is shown in FIG. 7. The system 120comprises environment sensing means 113 configured to determine theposition and orientation of the vehicle 103 within the environment 107and to determine one or more features and/or obstructions of theenvironment 107 or on a proposed route for the vehicle 103. Theenvironment sensing means 113 comprises a satellite navigation module203 which comprises a global navigation satellite system (GNSS) in theform of a Global Positioning System (GPS) receiver 702, stored digitalmaps 703 and a route planner 704 configured to determine a route independence of the current position of the vehicle 103 and a userselected destination.

To enhance data produced by the satellite navigation module 203, and toreplace that data when necessary, the environment sensing means 113additionally comprises an odometer or speedometer 709; and anaccelerometer 706, a gyroscope 707 and a magnetometer 708 which may formpart of an inertial measurement unit (IMU) 705. In addition, theenvironment sensing means 113 comprises one or more systems for sensingone or more features of the environment in the vicinity of the vehicle103, including a radar system 710 and a lidar system 711 that senses theenvironment by detection of reflected laser light. Distance sensors 712,such as those used for parking, or cameras 713 may be used to detectnearby obstructions, such as a vehicle in the route ahead of the vehicle103.

The cameras 713 and/or the lidar system 711 may form a part of anadvanced user assistance system or advanced driver assistance system(ADAS), as is known in the art.

An environment mapping means 714 determines the position and orientationof the vehicle 103 in dependence on data received from the environmentsensing means 113. For example, the position and orientation of thevehicle 103 may be determined from the satellite navigation system 203and knowledge of the path of the vehicle 103 along the proposed route asdetermined by the route planner 704. The environment mapping means 714may be configured to perform data fusion algorithms which process thedata from the various sources provided by the environment sensing means113. For example, the position and orientation of the vehicle 103determined from the satellite navigation system 203 may be enhanced bydead reckoning calculations performed in dependence on data receivedfrom the odometer or speedometer 709 and the IMU 705 or accelerometers706, gyroscopes 707 and magnetometer 708.

Dead reckoning may be performed to determine the position of the vehicle103 when GPS signals are unavailable, such as when the vehicle 103 iswithin a tunnel or between very tall buildings. However, dead reckoningmay also be used to enhance the accuracy of the position determinationfrom GPS signals. Likewise, the accuracy of the dead reckoning may beimproved by comparing positions determined from dead reckoning withpositions determined from the GPS signals, when GPS signals areavailable.

The position and orientation determination may also be enhanced by ahigh definition map that includes landmarks that may be compared withdata received from the radar system 710 or lidar system 711. The highdefinition map may also include information relating to maximum speedlimits and potential hazards such as road junctions that may require areduction in speed.

The environment mapping means 714 may also be arranged to obtain detailsof the route immediately ahead of the vehicle 103, including details ofbends in the roads, and changes in elevation of the road. Such detailsmay be obtained from high definition maps, which contain altitude data,and/or from a lidar system 711 and/or a radar system 710.

The environment mapping means 714 provides data to a processing means715 for the determination of a proposed position and orientation of thevirtual object 108 to be displayed. The data received by the processingmeans 715 may comprise the determined position and orientation of thevehicle 103, the current speed of the vehicle 103 and data indicative ofthe next portion of the route that the vehicle 103 is about tonegotiate, including changes in direction and elevation, and a maximumor suitable speed for the next portion of the route. The processingmeans 715 is configured to determine a proposed position and orientationof the virtual object 108 in dependence on the determined position andorientation of the vehicle 103, the data indicative of the next portionof the route and a previous proposed position and orientation of thevirtual object 108.

It will be appreciated that the process performed by processing means715 is one that is repeatedly performed in order to determine a seriesof positions and orientations for the virtual object 108, so that thevirtual object appears to be travelling ahead of the vehicle 103 alongthe proposed route.

The apparent position of the virtual object 108 within the environment107 is maintained within a limited distance from the vehicle 103, butmay be varied between lower and upper limits of, for example, 2 and 8metres. The apparent distance from the vehicle 103 to the virtual object108 is typically reduced at times when the environment mapping means 714indicates that the suitable speed for the next portion of the route isless than the current speed of the vehicle 103. Similarly, the apparentdistance is typically increased when the maximum or suitable speed forthe next portion of the route is greater than the current speed of thevehicle.

An eye position detection means 716 is arranged to receive image data,including representations of at least one eye 105 of the user 106, fromthe imaging means 114. The eye position detection means 716 isconfigured to analyse each of the images to generate the positional datarepresentative of a position of at least one eye 105 of the user 106.

A graphical image generation means 717 is configured to producegraphical image data in dependence on data received from the processingmeans 715, indicative of the proposed position and orientation of thevirtual object 108, and positional data received from the eye positiondetection means 716. The graphical image data produced by the graphicalimage generation means 717 is provided to the head-up display 102 tocause it to display the virtual object 108 so as to appear at theproposed position and with the proposed orientation with respect to theenvironment.

An illustration of how the graphical image data is produced is providedby FIG. 8, which shows a plan view of the vehicle 103 on a proposedroute 801. An object 802 representing the car 202 to be displayed on thehead-up display 102 is shown in FIG. 8 (in dotted outline) at a proposedposition 804 on the route 801 ahead of the vehicle 103. As discussedabove, the route 801 may be generated by the route planner 704 and aposition 803 of the vehicle 103 may be determined from data receivedfrom the GPS receiver 702 and/or other environment sensing means 113such as the IMU 705 and the odometer 709. The position 803 of thevehicle 103 is shown in the example of FIG. 8 at the centre of thevehicle 103, but it will be understood that the position 803 may bedefined to be at the position of another point on the vehicle 103.

The orientation of the object 802 may be represented by a directionvector d₁ and the orientation of the vehicle 103 may be represented by adirection vector d₂ as shown in FIG. 8.

The proposed position 804 of the object 802, relative to the position803 of the vehicle 103 is represented by a position vector s₁. Thepositional data representative of the position of the user's eyes 105from the imaging means 114 may be also represented by a position vectors₂. The position of the imaging means 114 from the position 803 of thevehicle 103 is a fixed displacement with a vector s₃. Therefore, aposition vector s₄ from the position of the user's eyes 105 to theproposed position 804 of the object 802 may be determined (as s₁-s₂-s₃)and the orientation of the object 802 as viewed by the user 106 may bedetermined as angle 805 between the vector d₁ and the vector s₄ from theposition of the user's eyes 105 to the proposed position 804.

The above described vectors and angles are shown in FIG. 8 as2-dimensional, but, in the present embodiment, in order for thedisplayed car 202 to appear to be correctly positioned in the exteriorenvironment 107 and resting on solid ground (such as the road 205 inFIG. 2), the vectors and angles are 3-dimensional.

The object 802 may be represented by a 3-dimensional model that definesthe shape of the car 202 to be presented on the head-up display 103.Therefore graphical data representing a two dimensional view of the car202 may be generated from: the 3-dimensional model; the distance fromthe eyes 105 of the user 106 to the proposed position 804 (i.e. |s₄|);and the angle 805.

Proposed positions, such as proposed position 804, may be determinedrepeatedly with a fixed period between each determination, to generate aseries of images for presentation on the head-up display 102. Followingthe determination of the proposed position 804, the next proposedposition 804A is determined to be on the route 801 a distance ahead ofthe proposed position 804. This distance depends on the speed of thevehicle 103 and a determined proposed speed for the vehicle 103 at theproposed position 804. For example, the proposed speed may be maximumlegal speed or suitable speed for the vehicle 103 at the proposedposition 804 on the route 801. The next proposed position 804A is chosensuch that if the speed of the vehicle 103 is less than the maximum speedor suitable speed for the vehicle then the distance from the currentproposed position 804 to the next proposed position 804A may be madelarger than the distance travelled by the vehicle 103 during the fixedperiod. Therefore, the distance from the vehicle 103 to the proposedposition 804A is increased. Similarly, if the speed of the vehicle 103is greater than the maximum speed or suitable speed for the vehicle thenthe distance from the current proposed position 804 to the next proposedposition 804A may be made smaller than the distance travelled by thevehicle 103 during the fixed period. Therefore, the distance from thevehicle 103 to the proposed position 804A is decreased. The distancebetween the vehicle 103 and the proposed positions (such as 804 and804A) may be increased and decreased within limits, such as a lowerlimit of 2 metres and an upper limit of 8 metres, as describedpreviously.

Apparatus 101 comprising the control means 104 is shown schematically inFIG. 9. The control means 114 comprises one or more electronicprocessors 902 and one or more electronic memory devices 903. A computerprogram 904 comprising instructions is stored in the memory device 903and the one or more electronic processors 902 are configured to executethe instructions to control the head-up display (102 in FIG. 1) of thevehicle 103, to cause it to display a representation of a car (202 inFIG. 2) as described herein.

In embodiments in which the control means 104 comprises severalprocessors 902, the processors may be located within a single module ormay be distributed over several different modules. For example, theprocess performed by eye position detection means 716 (shown in FIG. 7)may be performed by a processor 902 of the control means 104 that islocated within a camera 114 configured to capture images of the eyes 105of the user 106, while the process performed by the graphical imagegeneration means 717 (shown in FIG. 7), may be performed by a differentprocessor 902, located within a unit that includes the display device ofthe head-up display 102. In an alternative embodiment, the control means104 comprises a single processor 902 that performs the functions ofenvironment mapping, determination of position and orientation, andgraphical image generation (respectively 714, 715 and 717 shown in FIG.7).

The apparatus 101 may also comprise input/output means 905 for receivingand transmitting communications to other electronic devices. Theinput/output means 905 may comprise one or more transceivers forcommunicating with other devices over data buses, such as a controllerarea network bus (CAN bus) of the vehicle 103.

The computer program 904 may be transferred to the memory device 903 viaa non-transitory computer readable medium, such as a CD-ROM 906 or aportable memory device, or via a network, such as a wireless network.

A flowchart illustrating a method 1000, performable by the apparatus101, of controlling a head-up display of a vehicle is shown in FIG. 10.At block 1001 of the method 1000, positional data representative of aposition of at least one eye of a user of a vehicle is obtained. Forexample, the positional data may be obtained from the imaging means 114comprising one or more cameras arranged to capture images containingrepresentations of at least one of a user's eyes 105, so that theposition of the at least one eye is obtained from one or more capturedimages.

At block 1002, the method 1000 obtains environment data representativeof the environment external to the vehicle. For example, the environmentdata may comprise data that defines the contours of the routeimmediately ahead of the vehicle.

At block 1003, the method 1000 obtains status data representative of acurrent position and current orientation of the vehicle, and at block1004 a proposed position and proposed orientation for an object (such asobject 802 shown in FIG. 8) in dependence on the environment data andthe current position of the vehicle is determined. For example, a nextproposed position may be determined from a current proposed position asdescribed above with reference to FIG. 8. The proposed position andproposed orientation may be for a 3-dimensional object such as a car.

At block 1005, in dependence on the proposed position, the proposedorientation, the positional data and current orientation of the vehicle,the method 1000 generates image data for the head-up display for causingthe head-up display to display a virtual object so as to appear at theproposed position and with the proposed orientation with respect to theenvironment. For example, the image data may be generated as describedabove with reference to FIG. 8, and therefore the virtual object 108(shown in FIGS. 1 and 2) provides a view of a 3-dimensional object, suchas the displayed car 202 (shown in FIG. 2).

In an alternative embodiment, an alternative virtual object 108 (shownin FIG. 1) may be a simple 2-dimensional object, such as an arrow, whichhas a shape or orientation that changes to show the direction of theroute immediately ahead of the vehicle. However, like the virtual object108 in the form of the car 202, the size and apparent distance to thealternative virtual object 108 is controlled to convey varying speeds tothe user 106.

Additional processes that may be included within the method 1000 areshown in FIG. 11. After determining a proposed position for the objectat block 1004, it is determined, at block 1101, whether there is anobstruction at the proposed position or between the current position ofthe vehicle and the proposed position. For example, distance sensors712, a lidar system 711 or a radar system 710 may provide dataindicating that an obstruction, such as another vehicle, is between thevehicle 103 and the proposed position of the object. If there is such anobstruction present, the brightness of the virtual object is adjusted atblock 1102. Typically the brightness is reduced so that the user 106 isnot confused or distracted by seeing two vehicles that appear to sharethe same space, or apparently seeing the virtual object (i.e. the car202) through a vehicle that provides the obstruction. In an embodiment,the brightness is reduced to zero so that the virtual object is notvisible to the user. When the obstruction is no longer at the proposedposition or between the vehicle and the proposed position, thebrightness may be increased again so that the virtual object is onceagain visible.

In an embodiment, an alternative graphical element to the usual virtualobject is displayed, as indicated at block 1103, when the brightness ofthe virtual object is reduced at block 1102. For example, thealternative graphical element may comprise an arrow 602 as describedabove with reference to FIG. 6.

An embodiment of the method 1000 including additional processes isillustrated in the flowchart shown in FIG. 12. Following thedetermination of the proposed position and proposed orientation for anobject at block 1004, it is determined, at block 1201 whether theproposed position for the object is outside of a limit of the head-updisplay, so that the virtual object 108 (such as the car 202 shown inFIG. 2) is not present in the field of view of the head-up display 102.If it is outside of the limit of the head-up display, an alternativegraphical element is displayed at block 1202. The processes at blocks1001 to 1004 and blocks 1201 and 1202 are then repeatedly performeduntil it is determined at block 1201 that the virtual object 108 is onceagain within the limits of the head-up display.

When it is determined that the virtual object 108 is within the limitsof the head-up display at block 1201, the process at block 1005 isperformed wherein, in dependence on the proposed position, the proposedorientation, the positional data and current orientation of the vehicle,the method 1000 generates image data for the head-up display for causingthe head-up display to display a virtual object so as to appear at theproposed position and with the proposed orientation with respect to theenvironment. The processes at blocks 1001 to 1004, 1201 and 1005 arethen repeatedly performed until it is determined that the virtual object(such as virtual object 108) is no longer within the limits of thehead-up display at block 1201. An example of the method illustrated byFIG. 12 was described above with reference to FIG. 5.

Additional processes that may be included within an embodiment of themethod 1000 are shown in the flowchart of FIG. 13, these additionalprocesses may be performed before block 1004 or included as asub-routine within any of blocks 1002 to 1004 as may be desired. Atblock 1301, the method 1000 determines from the environment datapositions along a route where it is necessary to turn onto a differentroad or to change lane on a road. At block 1302, image data is generatedto cause an indication on the head-up display to provide a warning thata turn onto a different road or a change of lane is about to berequired. For example, the indication may comprise movement of thevirtual object 108 towards one side of the field of view 201 of thehead-up display 102 and/or, where the virtual object 108 represents avehicle, such as the car 202, the indication may comprise illuminationof a portion of the virtual image 108 that represents an indicator light304 of that vehicle. An example of this arrangement was described abovewith reference to FIG. 3.

An additional process that may be included within an embodiment of themethod 1000 is shown in the flowchart of FIG. 14. The process at block1401 obtaining speed data representative of a current speed of thevehicle. The speed data may be obtained from data received from anodometer or speedometer 609 or the GPS receiver 602. At block 1402,which may be performed as a sub-routine of block 1004 of the method1000, the proposed position and proposed orientation for the object aredetermined in dependence on the environment data, the current positionof the vehicle and the current speed of the vehicle. For example, theproposed position of the object may be determined from a previouslydetermined proposed position of the object and a displacement determinedfrom the speed of the vehicle in a direction determined by the proposedroute. However, as described above with reference to FIG. 8, theproposed position may further depend on the environment data, which mayindicate that an increase in vehicle speed is possible, in which casethe magnitude of the displacement may be increased, or that a reductionin vehicle speed is required, in which case the magnitude of thedisplacement may be reduced.

For purposes of this disclosure, it is to be understood that the controlmeans or controller(s) described herein can each comprise a control unitor computational device having one or more electronic processors. Avehicle and/or a system thereof may comprise a single control unit orelectronic controller or alternatively different functions of thecontroller(s) may be embodied in, or hosted in, different control unitsor controllers. A set of instructions could be provided which, whenexecuted, cause said controller(s) or control unit(s) to implement thecontrol techniques described herein (including the described method(s)).The set of instructions may be embedded in one or more electronicprocessors, or alternatively, the set of instructions could be providedas software to be executed by one or more electronic processor(s). Forexample, a first controller may be implemented in software run on one ormore electronic processors, and one or more other controllers may alsobe implemented in software run on or more electronic processors,optionally the same one or more processors as the first controller. Itwill be appreciated, however, that other arrangements are also useful,and therefore, the present disclosure is not intended to be limited toany particular arrangement. In any event, the set of instructionsdescribed above may be embedded in a computer-readable storage medium(e.g., a non-transitory storage medium) that may comprise any mechanismfor storing information in a form readable by a machine or electronicprocessors/computational device, including, without limitation: amagnetic storage medium (e.g., floppy diskette); optical storage medium(e.g., CD-ROM); magneto optical storage medium; read only memory (ROM);random access memory (RAM); erasable programmable memory (e.g., EPROM adEEPROM); flash memory; or electrical or other types of medium forstoring such information/instructions.

The blocks illustrated in the FIGS. 10 to 14 may represent steps in amethod and/or sections of code in the computer program 904. Theillustration of a particular order to the blocks does not necessarilyimply that there is a required or preferred order for the blocks and theorder and arrangement of the block may be varied. Furthermore, it may bepossible for some steps to be omitted.

Although embodiments of the present invention have been described in thepreceding paragraphs with reference to various examples, it should beappreciated that modifications to the examples given can be made withoutdeparting from the scope of the invention as claimed. For example, in analternative embodiment the head-up display is located in another type ofvehicle such as an aircraft, a boat or ship.

Features described in the preceding description may be used incombinations other than the combinations explicitly described.

Although functions have been described with reference to certainfeatures, those functions may be performable by other features whetherdescribed or not.

Although features have been described with reference to certainembodiments, those features may also be present in other embodimentswhether described or not.

Whilst endeavouring in the foregoing specification to draw attention tothose features of the invention believed to be of particular importanceit should be understood that the Applicant claims protection in respectof any patentable feature or combination of features hereinbeforereferred to and/or shown in the drawings whether or not particularemphasis has been placed thereon.

1. An apparatus for controlling a head-up display of a vehicle, theapparatus comprising a controller configured to: obtain positional datarepresentative of a position of an eye of a user of the vehicle; obtainenvironment data representative of an environment external to thevehicle; obtain status data representative of a current position of thevehicle; determine a proposed position and proposed orientation independence on the environment data and the status data; in dependence onthe proposed position, the proposed orientation and the positional data,generate image data for the head-up display for causing the head-updisplay to display a virtual object so as to appear at the proposedposition and with the proposed orientation with respect to theenvironment; and display an alternative graphical element in dependenceon the proposed position being outside of a limit of the head-up displayin which the virtual object is not present in a field of view of thehead-up display.
 2. The apparatus according to claim 1, wherein thestatus data is additionally representative of a current orientation ofthe vehicle and the controller is configured to generate image data independence on the current orientation of the vehicle.
 3. The apparatusaccording to claim 1, wherein the environment data comprises route datarepresentative of a route for the vehicle, the proposed position is onthe route and the proposed orientation is indicative of a directionalong the route.
 4. The apparatus according to claim 1, wherein thecontroller is configured to obtain speed data representative of acurrent speed of the vehicle, and determine the proposed position andproposed orientation in dependence on the environment data, the statusdata and the current speed of the vehicle.
 5. The apparatus according toclaim 1, wherein the controller is configured to adjust an apparentdistance between the vehicle and the virtual object.
 6. The apparatusaccording to claim 5, wherein the controller is configured to determinefrom the environment data a proposed speed for the vehicle at theproposed position, and to decrease the apparent distance between thevehicle and the virtual object in dependence on the current vehiclespeed being greater than the proposed speed.
 7. The apparatus accordingto claim 5, wherein the controller is configured to decrease theapparent distance between the vehicle and the virtual object independence on the environment data being indicative of the vehicleapproaching a section of a road/route having at least one of: a legalspeed limit which is less than the current speed of the vehicle, a bend,a road junction, and traffic moving slower than the vehicle.
 8. Theapparatus according to claim 5, wherein the controller is configured todetermine from the environment data a proposed speed for the vehicle atthe proposed position, and to increase the apparent distance between thevehicle and the virtual object in dependence on the current speed of thevehicle being less than the proposed speed.
 9. The apparatus accordingto claim 1, wherein the controller is configured to adjust a brightnessof the virtual object in dependence on a determination that anobstruction is at the proposed position or between the vehicle and theproposed position.
 10. The apparatus according to claim 9, wherein thecontroller is configured to prevent the display of the virtual object independence on a determination that an obstruction is at the proposedposition or between the vehicle and the proposed position.
 11. Theapparatus according to claim 9, wherein the controller is configured todisplay an alternative graphical element to the virtual object independence on a determination that an obstruction is at the proposedposition or between the vehicle and the proposed position. 12.(canceled)
 13. The apparatus according to claim 1, wherein thecontroller is configured to determine the proposed position and theproposed orientation for a 3-dimensional object and to generate theimage data for displaying the virtual object from a 3-dimensional modelof the 3-dimensional object in dependence on the positional data, thestatus data and the proposed orientation.
 14. The apparatus according toclaim 1, wherein the virtual object comprises a 2-dimensional virtualobject.
 15. (canceled)
 16. The apparatus according to claim 1, whereinthe alternative graphical element provides an indication of a directionof a route for the vehicle.
 17. The apparatus according to claim 1,wherein the controller is configured to determine, from the environmentdata, positions along a route where it is necessary to change directionor to turn onto a different road or to change of lane on a road whilethe vehicle is driven; and generate image data to cause an indication onthe head-up display to provide a warning that a change in direction or aturn onto a different road or a change of lane is about to be required.18. The apparatus according to claim 1, wherein the controller isconfigured to receive environment data from at least one of: a satellitenavigation module comprising a digitally stored map, one or moredistance sensors, a radar system, a lidar system, and a camera.
 19. Theapparatus according to claim 1, wherein the controller is configured todetermine the current position and/or the current orientation of thevehicle from data obtained from a satellite navigation device, aninertial measurement unit (IMU), an accelerometer, a gyroscope and anodometer. 20-24. (canceled)
 25. A method of controlling a head-updisplay of a vehicle, the method comprising: obtaining positional datarepresentative of a position of an eye of a user of the vehicle;obtaining environment data representative of the environment external tothe vehicle; obtaining status data representative of a current positionof the vehicle; determining a proposed position and proposed orientationin dependence on the environment data and the status data of thevehicle; in dependence on the proposed position, the proposedorientation and the positional data, generating image data for thehead-up display for causing the head-up display to display a virtualobject so as to appear at the proposed position and with the proposedorientation with respect to the environment; and displaying analternative graphical element in dependence on the proposed positionbeing outside of a limit of the head-up display in which the virtualobject is not present in a field of view of the head-up display. 26-29.(canceled)
 30. A computer program which when executed by a processorcauses the processor to perform the method of claim 25, wherein thecomputer program is stored on a non-transitory computer-readable storagemedium. 31-32. (canceled)
 33. A vehicle comprising the control apparatusof claim 1.